Patent Document 1 discloses a rotating electric machine controller for controlling a motor with two coil sets and an electric power steering device using the same. In the disclosure of Patent Document 1, high-potential switching element(s) of one or more phases in either one of two systems are controlled to be ON, and low-potential switching element(s) of one or more phases in the other system are controlled to be OFF, before the startup of the motor. Under such conditions, the presence/absence of a short-circuit between the systems is determined based on whether a phase current or two phase currents are increased.